The present invention involves a surgical device and methods of manufacture and use. More specifically, it involves a circumferential ablation device assembly and associated methods of manufacture and use. One aspect of the present invention specifically involves an assembly and method incorporating a circumferential band along an intermediate region of an expandable member""s working length for ablating a circumferential region of tissue engaged to the intermediate region at a location where a pulmonary vein extends from a left atrium.
The terms xe2x80x9cbody space,xe2x80x9d including derivatives thereof, is herein intended to mean any cavity or lumen within the body which is defined at least in part by a tissue wall. For example, the cardiac chambers, the uterus, the regions of the gastrointestinal tract, and the arterial or venous vessels are all considered illustrative examples of body spaces within the intended meaning.
The term xe2x80x9cbody lumen,xe2x80x9d including derivatives thereof, is herein intended to mean any body space which is circumscribed along a length by a tubular tissue wall and which terminates at each of two ends in at least one opening that communicates externally of the body space. For example, the large and small intestines, the vas deferens, the trachea, and the fallopian tubes are all illustrative examples of lumens within the intended meaning. Blood vessels are also herein considered lumens, including regions of the vascular tree between their branch points. More particularly, the pulmonary veins are lumens within the intended meaning, including the region of the pulmonary veins between the branched portions of their ostia along a left ventricle wall, although the wall tissue defining the ostia typically presents uniquely tapered lumenal shapes.
Many local energy delivery devices and methods have been developed for treating the various abnormal tissue conditions in the body, and particularly for treating abnormal tissue along body space walls which define various body spaces in the body. For example, various devices have been disclosed with the primary purpose of treating or recanalizing atherosclerotic vessels with localized energy delivery. Several prior devices and methods combine energy delivery assemblies in combination with cardiovascular stent devices in order to locally deliver energy to tissue in order to maintain patency in diseased lumens such as blood vessels. Endometriosis, another abnormal wall tissue condition which is associated with the endometrial cavity and is characterized by dangerously proliferative uterine wall tissue along the surface of the endometrial cavity, has also been treated by local energy delivery devices and methods. Several other devices and methods have also been disclosed which use catheter-based heat sources for the intended purpose of inducing thrombosis and controlling hemorrhaging within certain body lumens such as vessels. Detailed examples of local energy delivery devices and related procedures such as those of the types just described above are variously disclosed in the following references: U.S. Pat. No. 4,672,962 to Hershenson; U.S. Pat. No. 4,676,258 to InoKuchi et al.; U.S. Pat. No. 4,790,311 to Ruiz; U.S. Pat. No. 4,807,620 to Strul et al.; U.S. Pat. No. 4,998,933 to Eggers et al.; U.S. Pat. No. 5,035,694 to Kasprzyk et al.; U.S. Pat. No. 5,190,540 to Lee; U.S. Pat. No. 5,226,430 to Spears et al.; and U.S. Pat. No. 5,292,321 to Lee; U.S. Pat. No. 5,449,380 to Chin; U.S. Pat. No. 5,505,730 to Edwards; U.S. Pat. No. 5,558,672 to Edwards et al.; and U.S. Pat. No. 5,562,720 to Stem et al. ; U.S. Pat. No. 4,449,528 to Auth et al.; U.S. Pat. No. 4,522,205 to Taylor et al.; and U.S. Pat. No. 4,662,368 to Hussein et al.; U.S. Pat. No. 5,078,736 to Behl; and U.S. Pat. No. 5,178,618 to Kandarpa. The disclosures of these references are herein incorporated in their entirety by reference thereto.
Other prior devices and methods electrically couple fluid to an ablation element during local energy delivery for treatment of abnormal tissues. Some such devices couple the fluid to the ablation element for the primary purpose of controlling the temperature of the element during the energy delivery. Other such devices couple the fluid more directly to the tissue-device interface either as another temperature control mechanism or in certain other known applications as a carrier or medium for the localized energy delivery, itself. More detailed examples of ablation devices which use fluid to assist in electrically coupling electrodes to tissue are disclosed in the following references: U.S. Pat. No. 5,348,554 to Imran et al.; U.S. Pat. No. 5,423,811 to Imran et al.; U.S. Pat. No. 5,505,730 to Edwards; U.S. Pat. No. 5,545,161 to Imran et al.; U.S. Pat. No. 5,558,672 to Edwards et al.; U.S. Pat. No. 5,569,241 to Edwards; U.S. Pat. No. 5,575,788 to Baker et al.; U.S. Pat. No. 5,658,278 to Imran et al.; U.S. Pat. No. 5,688,267 to Panescu et al.; U.S. Pat. No. 5,697,927 to Imran et al.; U.S. Pat. No. 5,722,403 to McGee et al.; U.S. Pat. No. 5,769,846; and PCT Patent Application Publication No. WO 97/32525 to Pomeranz et al.; and PCT Patent Application Publication No. WO 98/02201 to Pomeranz et al. To the extent not previously incorporated above, the disclosures of these references are herein incorporated in their entirety by reference thereto.
Atrial Fibrillation
Cardiac arrhythmias, and atrial fibrillation in particular, persist as common and dangerous medical ailments associated with abnormal cardiac chamber wall tissue, and has been observed especially in the aging population. In patients with cardiac arrhythmia, abnormal regions of cardiac tissue do not follow the synchronous beating cycle associated with normally conductive tissue in patients with sinus rhythm. Instead, the abnormal regions of cardiac tissue aberrantly conduct to adjacent tissue, thereby disrupting the cardiac cycle into an asynchronous cardiac rhythm. Such abnormal conduction has been previously known to occur at various regions of the heart, such as, for example, in the region of the sino-atrial (SA) node, along the conduction pathways of the atrioventricular (AV) node and the Bundle of His, or in the cardiac muscle tissue forming the walls of the ventricular and atrial cardiac chambers.
Cardiac arrhythmias, including atrial arrhythmia, may be of a multiwavelet reentrant type, characterized by multiple asynchronous loops of electrical impulses that are scattered about the atrial chamber and are often self propagating. In the alternative or in addition to the multiwavelet reentrant type, cardiac arrhythmias may also have a focal origin, such as when an isolated region of tissue in an atrium fires autonomously in a rapid, repetitive fashion. Cardiac arrhythmias, including atrial fibrillation, may be generally detected using the global technique of an electrocardiogram (EKG). More sensitive procedures of mapping the specific conduction along the cardiac chambers have also been disclosed, such as, for example, in U.S. Pat. No. 4,641,649 to Walinsky et al. and Published PCT Patent Application No. WO 96/32897 to Desai. The disclosures of these references are herein incorporated in their entirety by reference thereto.
A host of clinical conditions may result from the irregular cardiac function and resulting hemodynamic abnormalities associated with atrial fibrillation, including stroke, heart failure, and other thromboembolic events. In fact, atrial fibrillation is believed to be a significant cause of cerebral stroke, wherein the abnormal hemodynamics in the left atrium caused by the fibrillatory wall motion precipitate the formation of thrombus within the atrial chamber. A thromboembolism is ultimately dislodged into the left ventricle which thereafter pumps the embolism into the cerebral circulation where a stroke results. Accordingly, numerous procedures for treating atrial arrhythmias have been developed, including pharmacological, surgical, and catheter ablation procedures.
Several pharmacological approaches intended to remedy or otherwise treat atrial arrhythmias have been disclosed, such as for example according to the disclosures of the following references: U.S. Pat. No. 4,673,563 to Beme et al.; U.S. Pat. No. 4,569,801 to Molloy et al.; and also xe2x80x9cCurrent Management of Arrhythimiasxe2x80x9d (1991) by Hindricks, et al. However, such pharmacological solutions are not generally believed to be entirely effective in many cases, and are even believed in some cases to result in proarrhythmia and long term inefficacy. The disclosures of these references are herein incorporated in their entirety by reference thereto.
Several surgical approaches have also been developed with the intention of treating atrial fibrillation. One particular example is known as the xe2x80x9cmaze procedure,xe2x80x9d as is disclosed by Cox, JL et al. in xe2x80x9cThe surgical treatment of atrial fibrillation. I. Summaryxe2x80x9d Thoracic and Cardiovascular Surgery 101(3), pp. 402-405 (1991); and also by Cox, J L in xe2x80x9cThe surgical treatment of atrial fibrillation. IV. Surgical Techniquexe2x80x9d, Thoracic and Cardiovascular Surgery 101(4), pp. 584-592 (1991). In general, the xe2x80x9cmazexe2x80x9d procedure is designed to relieve atrial arrhythmia by restoring effective atrial systole and sinus node control through a prescribed pattern of incisions about the tissue wall. In the early clinical experiences reported, the xe2x80x9cmazexe2x80x9d procedure included surgical incisions in both the right and the left atrial chambers. However, more recent reports predict that the surgical xe2x80x9cmazexe2x80x9d procedure may be substantially efficacious when performed only in the left atrium, such as is disclosed in Sueda et al., xe2x80x9cSimple Left Atrial Procedure for Chronic Atrial Fibrillation Associated With Mitral Valve Diseasexe2x80x9d (1996). The disclosure of these cited references are herein incorporated in their entirety by reference thereto.
The xe2x80x9cmaze procedurexe2x80x9d as performed in the left atrium generally includes forming vertical incisions from the two superior pulmonary veins and terminating in the region of the mitral valve annulus, traversing the region of the inferior pulmonary veins en route. An additional horizontal line also connects the superior ends of the two vertical incisions. Thus, the atrial wall region bordered by the pulmonary vein ostia is isolated from the other atrial tissue. In this process, the mechanical sectioning of atrial tissue eliminates the arrhythmogenic conduction from the boxed region of the pulmonary veins and to the rest of the atrium by creating conduction blocks within the aberrant electrical conduction pathways. Other variations or modifications of this specific pattern just described have also been disclosed, all sharing the primary purpose of isolating known or suspected regions of arrhythmogenic origin or propagation along the atrial wall.
While the xe2x80x9cmazexe2x80x9d procedure and its variations as reported by Cox and others have met some success in treating patients with atrial arrhythmia, its highly invasive methodology is believed to be prohibitive in most cases. However, these procedures have provided a guiding principle that electrically isolating faulty cardiac tissue may successfully prevent atrial arrhythmia, and particularly atrial fibrillation caused by arrhythmogenic conduction arising from the region of the pulmonary veins.
Less invasive catheter-based approaches to treat atrial fibrillation have been disclosed which implement cardiac tissue ablation for terminating arrhythmogenic conduction in the atria. Examples of such catheter-based devices and treatment methods have generally targeted atrial segmentation with ablation catheter devices and methods adapted to form linear or curvilinear lesions in the wall tissue which defines the atrial chambers. Some specifically disclosed approaches provide specific ablation elements which are linear over a defined length intended to engage the tissue for creating the linear lesion. Other disclosed approaches provide shaped or steerable guiding sheaths, or sheaths within sheaths, for the intended purpose of directing tip. ablation catheters toward the posterior left atrial wall such that sequential ablations along the predetermined path of tissue may create the desired lesion. In addition, various energy delivery modalities have been disclosed for forming atrial wall lesions, and include use of microwave, laser, ultrasound, thermal conduction, and more commonly, radiofrequency energies to create conduction blocks along the cardiac tissue wall.
Further more detailed examples of ablation device assemblies and methods for creating lesions along an atrial wall are disclosed in the following U.S. Patent references: U.S. Pat. No. 4,898,591 to Jang et al.; U.S. Pat. No. 5,104,393 to Isner et al.; U.S. Pat. No. 5,427,119; U.S. Pat. No. 5,487,385 to Avitall; U.S. Pat. No. 5,497,119 to Swartz et al.; U.S. Pat. No. 5,545,193 to Fleischman et al.; U.S. Pat. No. 5,549,661 to Kordis et al.; U.S. Pat. No. 5,575,810 to Swanson et al.; U.S. Pat. No. 5,564,440 to Swartz et al.; U.S. Pat. No. 5,592,609 to Swanson et al.; U.S. Pat. No. 5,575,766 to Swartz et al.; U.S. Pat. No. 5,582,609 to Swanson; U.S. Pat. No. 5,617,854 to Munsif; U.S. Pat. No 5,687,723 to Avitall; U.S. Pat. No. 5,702,438 to Avitall. To the extent not previously incorporated above, the disclosures of these references are herein incorporated in their entirety by reference thereto.
Other examples of such ablation devices and methods are disclosed in the following Published PCT Patent Applications: WO 93/20767 to Stern et al.; WO 94/21165 to Kordis et al.; WO 96/10961 to Fleischman et al.; WO 96/26675 to Klein et al.; and WO 97/37607 to Schaer. To the extent not previously incorporated above, the disclosures of these references are herein incorporated in their entirety by reference thereto.
Additional examples of such ablation devices and methods are disclosed in the following published articles: xe2x80x9cPhysics and Engineering of Transcatheter Tissue Ablationxe2x80x9d, Avitall et al., Journal of American College of Cardiology, Volume 22, No. 3:921-932 (1993); and xe2x80x9cRight and Left Atrial Radiofrequency Catheter Therapy of Paroxysmal Atrial Fibrillation,xe2x80x9d Haissaguerre, et al., Journal of Cardiovascular Electrophysiology 7(12), pp. 1132-1144 (1996). The disclosures of these references are herein incorporated in their entirety by reference thereto.
In addition to those known assemblies just summarized above, additional tissue ablation device assemblies have also been recently developed for the specific purpose of ensuring firm contact and consistent positioning of a linear ablation element along a length of tissue by anchoring the element at least at one predetermined location along that length, such as in order to form a xe2x80x9cmazexe2x80x9d-type lesion pattern in the left atrium. One example of such assemblies includes an anchor at each of two ends of a linear ablation element in order to secure those ends to each of two predetermined locations along a left atrial wall, such as at two adjacent pulmonary veins, so that tissue may be ablated along the length of tissue extending therebetween.
In addition to attempting atrial wall segmentation with long linear lesions for treating atrial arrhythmia, other ablation device and method have also been disclosed which are intended to use expandable members such as balloons to ablate cardiac tissue. Some such devices have been disclosed primarily for use in ablating tissue wall regions along the cardiac chambers. Other devices and methods have been disclosed for treating abnormal conduction of the left-sided accessory pathways, and in particular associated with xe2x80x9cWolff-Parkinson-Whitexe2x80x9d syndrome various such disclosures use a balloon for ablating from within a region of an associated coronary sinus adjacent to the desired cardiac tissue to ablate. Further more detailed examples of devices and methods such as of the types just described are variously disclosed in the following published references: Fram et al., in xe2x80x9cFeasibility of RF Powered Thermal Balloon Ablation of Atrioventricular Bypass Tracts via the Coronary Sinus: In vivo Canine Studies,xe2x80x9d PACE, Vol. 18, p 1518-1530 (1995); xe2x80x9cLong-term effects of percutaneous laser balloon ablation from the canine coronary sinusxe2x80x9d, Schuger CD et al., Circulation (1992) 86:947-954; and xe2x80x9cPercutaneous laser balloon coagulation of accessory pathwaysxe2x80x9d, McMath L P et al., Diagn Ther Cardiovasc Interven 1991; 1425:165-171. The disclosures of these references are herein incorporated in their entirety by reference thereto.
Arrhythmias Originating from Foci in Pulmonary Veins
Various modes of atrial fibrillation have also been observed to be focal in nature, caused by the rapid and repetitive firing of an isolated center within cardiac muscle tissue associated with the atrium. Such foci may act as either a trigger of atrial fibrillatory paroxysmal or may even sustain the fibrillation. Various disclosures have suggested that focal atrial arrhythmia often originates from at least one tissue region along one or more of the pulmonary veins of the left atrium, and even more particularly in the superior pulmonary veins.
Less-invasive percutaneous catheter ablation techniques have been disclosed which use end-electrode catheter designs with the intention of ablating and thereby treating focal arrhythmias in the pulmonary veins. These ablation procedures are typically characterized by the incremental application of electrical energy to the tissue to form focal lesions designed to terminate the inappropriate arrhythmogenic conduction.
One example of a focal ablation method intended to treat focal arrhythmia originating from a pulmonary vein is disclosed by Haissaguerre, et al. in xe2x80x9cRight and Left Atrial Radiofrequency Catheter Therapy of Paroxysmal Atrial Fibrillationxe2x80x9d in Journal of Cardiovascular Electrophysiology 7(12), pp. 1132-1144 (1996) (previously incorporated by reference above). Haissaguerre, et al. discloses radiofrequency catheter ablation of drugrefractory paroxysmal atrial fibrillation using linear atrial lesions complemented by focal ablation targeted at arrhythmogenic foci in a screened patient population. The site of the arrhythmogenic foci were generally located just inside the superior pulmonary vein, and the focal ablations were generally performed using a standard 4 mm tip single ablation electrode.
Another focal ablation method of treating atrial arrhythmias is disclosed in Jais et al., xe2x80x9cA focal source of atrial fibrillation treated by discrete radiofrequency ablation,xe2x80x9d Circulation 95:572-576 (1997). The disclosure of this reference is herein incorporated in its entirety by reference thereto. Jais et al. discloses treating patients with paroxysmal arrhythmias originating from a focal source by ablating that source. At the site of arrhythmogenic tissue, in both right and left atria, several pulses of a discrete source of radiofrequency energy were applied in order to eliminate the fibrillatory process.
Other assemblies and methods have been disclosed addressing focal sources of arrhythmia in pulmonary veins by ablating circumferential regions of tissue either along the pulmonary vein, at the ostium of the vein along the atrial wall, or encircling the ostium and along the atrial wall. More detailed examples of device assemblies and methods for treating focal arrhythmia as just described are disclosed in Published PCT Patent Application No. WO 99/02096 to Diederich et al., and also in the following pending U.S. patent applications Ser. No. 08/889,798 for xe2x80x9cCircumferential Ablation Device Assemblyxe2x80x9d to Michael D. Lesh et al., filed Jul. 8, 1997; U.S. Ser. No. 08/889,835 for xe2x80x9cDevice and Method for Forming a Circumferential Conduction Block in a Pulmonary Veinxe2x80x9d to Michael D. Lesh, filed Jul. 8, 1997; U.S. Ser. No. 09/199,736 for xe2x80x9cCircumferential Ablation Device Assemblyxe2x80x9d to Chris J. Diederich et al., filed Feb. 3, 1998; and U.S. Ser. No. 09/260,316 for xe2x80x9cDevice and Method for Forming a Circumferential Conduction Block in a Pulmonary Veinxe2x80x9d to Michael D. Lesh.
Another specific device assembly and method which is intended to treat focal atrial fibrillation by ablating a circumferential region of tissue between two seals in order to form a conduction block to isolate an arrhythmogenic focus within a pulmonary vein is disclosed in U.S. Pat. No. 5,938,660 and a related Published PCT Patent Application No. WO 99/00064. The disclosures of these references are herein incorporated in their entirety by reference thereto.
It is an object of the invention to provide a circumferential ablation device assembly, and related method of manufacture and use, which ablates a circumferential region of tissue at a location where a pulmonary vein extends from an atrium by ablatively coupling an ablative fluid medium within an expandable member to the circumferential region of tissue across a circumferential band which circumscribes an intermediate region of the expandable member and engages the circumferential region of tissue when the expandable member is expanded.
It is another object of the invention to provide such a circumferential ablation device assembly, and related methods of use and manufacture, wherein the intermediate region of the expandable member""s working length is constructed at least in part of a porous fluoropolymer material.
It is a further object of the invention to provide such an expandable member with the porous fluoropolymer material along the intermediate region and also with first and second end portions of the working length that do not include a fluoropolymer.
It is another object of the invention to provide a circumferential ablation device assembly, and related methods of manufacture and use, which ablatively couples an ablation element to only a region of tissue engaged to an intermediate region between two end portions along a working length of an expandable member.
It is another object of the invention to provide a medical device assembly which ablatively couples an ablative fluid medium from within an expandable member to only a region of tissue engaged to only a fluid permeable section along the working length of the expandable member.
It is a further object of the invention to provide a circumferential ablation device assembly, and related methods of use and manufacture, that includes a balloon with elastomeric first and second end portions along its working length and also with a fluid permeable circumferential band circumscribing an intermediate region between those end portions.
It is a further object of the invention to provide a circumferential ablation device assembly, and related methods of use and manufacture, that includes a balloon having a fluid permeable fluoropolymer that is integral along the balloon""s working length and includes an insulator on each of two end portions of the working length such that only a circumferential band circumscribing an intermediate region between the end portions is left permeable. It is a further object to provide such a balloon with the two end portions impregnated with a filler as fluid insulation.
It is a further object of the invention to provide a circumferential ablation device assembly, and related methods of use and manufacture, that includes an expandable member having a working length constructed of an elastomeric wall that is constructed to be fluid permeable along only a circumferential band which circumscribes an intermediate region located between two end portions of the working length.
It is a further object of the invention to provide a circumferential ablation device assembly, and related methods of use and manufacture, that includes a balloon with a fluoropolymeric material that is integral along the balloon""s working length while only an intermediate region between two end portions of the working length is fluid permeable to allow for ablative coupling of an ablation medium across the fluoropolymeric material.
It is a further object of the invention to provide a circumferential ablation device assembly, and related methods of use and manufacture, that includes a balloon having a working length with relatively elastic first and second end portions and a relatively inelastic intermediate region between the first and second end portions, and which ablates only a circumferential region of tissue surrounding the intermediate region when the balloon is inflated.
It is a further object of the invention to provide a medical device catheter having a balloon with a working length that has a porous fluoropolymeric permeable section and also an elastomeric section.
It is a further object of the invention to provide such a catheter where the permeable fluoropolymer section is between two elastomeric end portions of the working length.
It is a further object of the invention to provide a circumferential ablation member with an expandable member having a taper along the working length and also with an ablation element coupled to a circumferential area surrounding the taper along the working length.
It is also a further object of the invention to provide a circumferential ablation member which an expandable member that is adapted to seat at a pulmonary vein ostium such that an ablation circumferential band surrounding the working length is aligned with and ablates a region of tissue along the ostium.
It is a further object of the invention to provide a circumferential ablation member for ablating a circumferential region of tissue along a pulmonary vein ostium and which includes an expandable member with a working length having two end portions that have larger outer diameters than an intermediate region of the working length that includes an ablative circumferential band which is adapted to seat at the pulmonary vein ostium.
Other objects of the invention are contemplated which would be apparent to one of ordinary skill based upon the totality of this disclosure, including without limitation the following summary of various modes, aspects, features, and variations of the particular embodiments.
In one mode of the invention, a circumferential ablation device assembly includes an elongate body with a circumferential ablation member along its distal end portion having an expandable member. The expandable member is located along the distal end portion of the elongate body, and is expandable along a working length which encloses at least in part a fluid chamber that is adapted to fluidly couple to a pressurizeable source of fluid. The working length also has first and second end portions and an intermediate region extending between the end portions. The end portions are substantially non-permeable to fluid, whereas the intermediate region is fluid permeable. With the working length expanded to a radially expanded condition, the intermediate region has an expanded outer diameter which is adapted to radially engage the circumferential region of tissue. The working length is thus adapted to allow fluid to pass from within the fluid chamber and outwardly into the permeable section of the intermediate region where it may be ablatively coupled to the engaged circumferential region of tissue.
In one aspect of this mode, the circumferential ablation member includes an ablation electrode element that is constructed to electrically couple to a volume of pressurized electrically conductive fluid passing from within the fluid chamber and into the permeable section of the intermediate region of the working length. Accordingly, current from the electrode element flows through the electrically conductive fluid and outwardly from the ablation member only through the permeable section along the intermediate region and into the circumferential region of tissue for ablation there.
In another aspect of this mode, the permeable section is constructed from a substantially non-permeable material that has a plurality of apertures formed therethrough which form pores to render that section permeable, whereas in another aspect the permeable section is instead constructed from an inherently porous material with the permeability arising from a plurality of pores that are integral to the porous material.
In another aspect of this mode, the permeable section comprises a porous fluoropolymer material, and may be more particularly a porous polytetrafluoroethylene material.
In another aspect of this mode, the expandable member is an inflatable balloon. The balloon is inflatable with pressurized fluid in order to expand from the radially collapsed condition to the radially expanded condition.
In one particular beneficial construction, the balloon along the intermediate region is constructed at least in part from a porous fluoropolymer material which forms the permeable section, and along the first and second end portions the balloon is constructed at least in part from an elastomer.
In another aspect of this mode, the permeable section forms a circumferential band which circumscribes the working length along the intermediate region. In one particular variation of this aspect, the circumferential band has a band length relative to the longitudinal axis and which is substantially shorter than the working length, and may be less than two-thirds the working length or even one-half of the working length.
In another aspect of this mode, the working length has a proximal end and a distal end and also has a tapered shape with a distally reducing outer diameter from the proximal end to the distal end. In one more particular beneficial variation, the tapered shape is xe2x80x9cpearxe2x80x9d-shaped and has a contoured surface between the proximal end and the distal end with a relatively xe2x80x9cforwardxe2x80x9d or xe2x80x9cdistalxe2x80x9d-looking face along the contoured surface adjacent the proximal end. Further to this variation, the permeable section is provided along a distally-looking face and is adapted to be advanced distally against a circumferential region of tissue when expanded, such as in order to ablate a region of tissue along a posterior left atrial wall which surrounds a pulmonary vein ostium and isolates the associated vein from a substantial portion of the left atrium.
Another mode of the invention provides a medical catheter assembly with a balloon positioned along a distal end portion of an elongate body which ablatively couples an ablation element to tissue via an ablative medium provided by a fluid along a fluid permeable portion of the balloon. The balloon defines a fluid chamber and has a working length that is expandable with a volume of pressurized fluid from a radially collapsed condition having a radially collapsed profile to a radially expanded condition having a radially expanded profile which is larger than the radially collapsed profile. The working length further includes a non-permeable section and a permeable section. The non-permeable section is constructed to substantially prevent the pressurized fluid from passing from within the fluid chamber and outwardly through and from the balloon in the radially expanded condition. The permeable section is constructed at least in part of a porous material having a plurality of pores. In the radially expanded condition the pores are constructed to substantially allow the pressurized fluid to pass from within the enclosed chamber and outwardly from the balloon through the permeable section.
In one aspect of this mode, the porous material is constructed at least in part from a porous fluoropolymer material and the plurality of pores are integrally formed in the porous fluoropolymer material.
In one beneficial variation of this aspect, the porous fluoropolymer material includes a porous polytetrafluoroethylene material. The pores according to this variation may be formed by and between a plurality of nodes which are interconnected by a plurality of fibrils that make up the polytetrafluoroethylene material, and may be located along a length of the porous polytetrafluoroethylene material which extends along both the non-permeable and permeable sections.
According to the polytetrafluoroethylene embodiment providing the pores along both the permeable and non-permeable sections, the pores along the non-permeable section are substantially blocked and non-permeable to the pressurized fluid within the fluid chamber and the pores along the permeable section are substantially open and permeable to pressurized fluid within the fluid chamber. Further to this embodiment, the pores along the non-permeable section may be blocked with an insulator material, which may be a polymer, or more specifically an elastomer in order to provide the working length of the balloon elastomeric qualities during in vivo use. In further embodiments, the insulator material may be a deposited material, such as plasma deposited materials, vapor deposited materials, ion beam deposited materials, or sputter coated materials, or may be a dip-coated material, or may be a thermoplastic material which is melted to the porous polytetrafluoroethylene material along the non-permeable section. In still further embodiments, the insulator material may be a coating over the outer surface of the porous polytetrafluoroethylene, such as a tubular material that may be an elastomer which is coaxially disposed relative to the non-permeable section, or may be a filler material within the pores along the non-permeable section.
In one specific beneficial variation, the porous polytetrafluoroethylene material is formed in a porous tube which is relatively non-compliant, and the tubular material further comprises an elastomer which is relatively compliant, such that the balloon in the radially collapsed condition is characterized by the porous polytetrafluoroethylene material in a folded condition and also by the tubular material in a relatively non-stretched condition, and the balloon in the radially expanded condition is characterized by the porous polytetrafluoroethylene material in an unfolded condition and also by the tubular material in a radially stretched condition.
In another variation of the porous polytetrafluoroethylene aspect, the porous material is formed from a tape which is oriented in a helical pattern with adjacent windings which are fused to form a continuous porous tube that defines at least in part the fluid chamber.
In another aspect of this mode, the working length is constructed at least in part from a polytetrafluoroethylene material having a length which extends along both the non-permeable and permeable sections. The polytetrafluoroethylene material according to this aspect is substantially non-porous along the non-permeable section, and is porous along the permeable section to thereby form the porous material.
In one variation of this aspect, the polytetrafluoroethylene material along the non-permeable section includes a plurality of non-permeable pores. The non-permeable pores are sufficiently small to prevent passage of the pressurized fluid from within the fluid chamber and outwardly from the balloon through the non-permeable section, and the polytetrafluoroethylene material along that section is therefore effectively non-porous. In a further more detailed embodiment of this variation, the plurality of pores along the permeable section are formed by and between a first plurality of nodes which are interconnected by a first plurality of fibrils, whereas the plurality of non-permeable pores are formed by and between a second plurality of nodes and interconnecting fibrils.
In another variation of the polytetrafluoroethylene material aspect, the material is expanded from a cured state along the permeable section and is relatively un-expanded and substantially in the cured state along the non-permeable section, such as for example being stretched and unstretched in the permeable and non-permeable sections, respectively.
In another aspect of this mode, the working length includes first and second end portions with an intermediate region extending therebetween. The first end portion includes the non-permeable section, the intermediate region includes the permeable section, and the second end portion includes a second non-permeable section of similar construction to the first non-permeable section.
In one beneficial variation of this aspect, the permeable section forms a circumferential band which circumscribes the working length along the intermediate region. In the radially expanded condition the intermediate region is constructed to radially engage a circumferential region of tissue along a body space wall of a body space, whereas the first and second end portions are further constructed to radially engage first and second adjacent regions of tissue, respectively, on opposite sides of the circumferential region of tissue. The permeable section is adapted to allow a volume of electrically conductive fluid to pass from within the fluid chamber and outwardly from the balloon through the pores. The assembly according to this beneficial variation further includes an ablation electrode which is constructed to electrically couple with the electrically conductive fluid within the fluid chamber and therefore to the circumferential region of tissue as the electrically conductive fluid flows outwardly from the balloon through the permeable section. According to this beneficial assembly, the electrical coupling from the ablation electrode and through the volume of electrically conductive fluid passing through the permeable section is substantially isolated to the circumferential region of tissue engaged by the intermediate region and is substantially shielded from the adjacent regions of tissue by the first and second end portions.
In another aspect of this mode, the non-permeable and permeable sections are located longitudinally adjacent each other along the working length relative to the longitudinal axis, and in one particular variation the permeable section is located distally adjacent the non-permeable section.
In another aspect of this mode, the working length has a proximal section and a distal section and a tapered shape with a distally reducing outer diameter from the proximal section to the distal section, and the permeable section is located along the tapered region. In one particular variation of this aspect, the permeable section forms a circumferential band which circumscribes the working length along the taper.
In another aspect of this mode, the permeable section is further constructed to allow a volume of electrically conductive fluid to pass from within the fluid chamber and outwardly through and from the balloon through the pores, and the assembly further includes an ablation electrode which is constructed to electrically couple to the volume of electrically conductive fluid within the fluid chamber.
Another mode of the invention is a method for forming a medical balloon catheter device assembly which is adapted to deliver a volume of fluid to a region of tissue in a body. This method includes constructing a fluid permeable tube having a permeable section formed at least in part from a porous material. This construction uses a porous material having a plurality of pores which are adapted to allow a volume of pressurized fluid to pass from within and outwardly through the tube, and further results in a tubular construction having a non-permeable section which is adapted to substantially prevent the volume of pressurized fluid from passing from within and outwardly through the tube. This method further includes securing the fluid permeable tube to a distal end portion of an elongate catheter body in order to form a balloon which defines a pressurizeable fluid chamber over the catheter body and which includes a working length that is adapted to radially expand from a radially collapsed condition to a radially expanded condition when the fluid chamber is filled with the pressurized fluid. The method also includes coupling the pressurizeable fluid chamber with a distal port of a fluid passageway that extends along the catheter body between the distal port and a proximal port along the proximal end portion of the elongate catheter body which is adapted to couple to a pressurizeable fluid source, and also includes positioning the permeable section along the working length.
One aspect of this method mode further includes forming a taper along the working length of the balloon having a distally reducing outer diameter, and positioning the permeable section along the taper. The non-permeable section may also be positioned along the taper.
Another aspect of this method includes constructing the fluid permeable tube at least in part from a porous fluoropolymer having a plurality of voids which form the pores.
One variation of this aspect also includes constructing the porous fluoropolymer to include a plurality of nodes which are interconnected with fibrils to form a node-fibril network such that the plurality of voids are formed between the nodes and interconnecting fibrils.
Another aspect of this method mode includes constructing an ablation electrode to electrically couple to an electrical current source and also to the permeable section when the pressurizeable fluid chamber is filled with an electrically conductive fluid.
One variation of this aspect further includes securing the ablation electrode to the distal end portion of the elongate catheter body, and securing the fluid permeable tube to the elongate catheter body on opposite sides of the ablation electrode such that the ablation electrode is positioned within the fluid chamber.
Another aspect of this method mode includes constructing the fluid permeable tube such that both the permeable and non-permeable sections are formed at least in part from the porous material.
One variation of this aspect includes forming the fluid permeable tube such that the is plurality of pores are provided along both the permeable and the non-permeable sections, and substantially blocking the pores along the non-permeable section such that the blocked pores are substantially non-permeable to the volume of fluid when the fluid is pressurized.
One more particular embodiment of this variation includes blocking the pores along the non-permeable section with an insulator material, such as by dip coating the non-permeable section with the insulator material, melting the insulator material to the non-permeable section, or depositing the insulator material along the non-permeable section.
Another more particular embodiment of the insulating variation includes substantially blocking the pores along both the permeable section and the non-permeable section with the insulator material, and then selectively removing the insulator material such that the pores along the permeable section are left open and un-blocked and the pores along the non-permeable section are left blocked. The insulation may be selectively removed in one beneficial method by dissolving the insulator material along the permeable section with a solvent, which process may further include selectively masking the insulator material along the non-permeable section from being exposed to and dissolved by the solvent.
Another mode of the invention includes a method for treating a region of tissue within a body by expanding a balloon from a radially collapsed condition to a radially expanded condition with a volume of pressurized fluid within a fluid chamber defined at least in part by the balloon, forcing the pressurized fluid from within the fluid chamber and outwardly from the balloon through a plurality of pores provided along a permeable section of the balloon, and substantially blocking the pressurized fluid from passing outwardly from and through the balloon along a non-permeable section of the balloon.
One aspect of this method further includes engaging the permeable section with a region of tissue and then forcing the pressurized fluid outwardly from the balloon through the pores along the permeable section and into the region of tissue. Further to this aspect, the pressurized fluid is forced outwardly from the balloon through the permeable section by weeping the fluid into the region of tissue without forming pressurized jets of fluid into the region of tissue.
Another aspect of this method includes engaging the permeable section with a circumferential region of tissue along a body space wall which defines at least in part a body space, and then forcing the pressurized fluid outwardly from the balloon through the pores along the permeable section and in a circumferential pattern into the circumferential region of tissue. One beneficial variation of this aspect of the method includes engaging the permeable section with a circumferential region of tissue along a pulmonary vein or with a circumferential region of tissue which surrounds a pulmonary vein ostium along a posterior left atrial wall. Another beneficial variation includes electrically coupling an ablation electrode to the pressurized fluid which is an electrically conductive fluid, and ablating the circumferential region of tissue with the pressurized fluid as it passes outwardly form the balloon through the permeable section and into the circumferential region of tissue. Further to this variation, the fluid may be passed to the circumferential region of tissue while substantially shielding the adjacent regions of tissue from electrically coupling to the ablation electrode via the pressurized fluid as it passes outwardly from the balloon through the permeable section and into the circumferential region of tissue. A further more detailed embodiment of this shielding variation includes radially engaging the non-permeable section with an adjacent region of tissue adjacent to the circumferential region of tissue engaged with the permeable section. This more detailed embodiment of the method may further include radially engaging a second non-permeable section with a second adjacent region of tissue which is adjacent to the circumferential region of tissue opposite the first adjacent region of tissue.
Another mode of the invention provides a circumferential ablation member with an expandable member constructed of two expandable elements along each of two end portions of the expandable member and a tubular member extending between the expandable elements which includes a circumferential band that is fluid permeable, wherein a fluid chamber is formed by the expandable elements and the tubular member extending therebetween, and such that fluid from the fluid chamber may be ablatively coupled to a circumferential region of tissue engaged by the circumferential band.
In one aspect of this mode, an electrode is adapted to be electrically coupled to the fluid within the chamber and thus to tissue engaged by the permeable circumferential band. In one variation of this aspect, the electrode is provided along an internal catheter shaft extending between the expandable elements.
In another mode, a medical catheter assembly has an expandable member that encloses a fluid chamber and also an inner expansion element such that the expansion element is adapted to expand a first portion of the expandable member""s working length to a different outer diameter than a second portion of the working length.
In one aspect of this mode, the working length of the expandable member further comprises a circumferential band which is permeable to the fluid within the fluid chamber.
In another aspect of this mode, the expandable member encloses first and second inner expansion elements. A tubular wall extends between those outer surfaces to enclose the fluid chamber. The working length of the expandable member includes an intermediate region constructed of the tubular wall, and also first and second end portions on opposite sides of the intermediate region, wherein the first and second inner expansion elements are located along the first and second end portions.
In a further variation of this aspect, the inner expansion elements are adapted to expand to different outer diameters such that the working length is tapered between the first and second end portions, and more particularly in one variation so that the working length has a distally reducing outer diameter.
In another mode, a circumferential ablation device assembly and method provide an elongate body with a circumferential ablation member on the distal end portion that includes a first expandable member, and a second expandable member is further provided along the distal end portion in a longitudinally spaced location relative to the first expandable member. An ablation element cooperates with at least one of the first and second expandable members in order to ablatively couple to tissue engaged therewith in the expanded condition. In one particular aspect of this mode, the ablation element cooperates with the first expandable member which is distal to the second expandable member on the distal end portion, and ablatively couples to tissue engaged by the first expandable member.